1. Technical Field
The present invention relates to a measurement apparatus and a measurement method.
2. Related Art
A known waveform generator generates a signal having a waveform that corresponds to waveform data and a known digitizer acquires waveform data indicating the waveform of a signal input thereto. Conventionally, such a waveform generator and digitizer generate and acquire a signal having a frequency that is approximately from tens of megahertz to hundreds of megahertz.    Japanese Patent Application Publication No. 2010-117349    Japanese Patent Application Publication No. 2008-286699
However, in recent years, waveform generators and digitizers have been developed that generate and acquire signals having a frequency from several gigahertz to tens of gigahertz. Such a waveform generator and digitizer used for high frequency signals include internal circuits with frequency characteristics that greatly affect the accuracy of the generated signal and of the acquired signal. Accordingly, the waveform generator and digitizer must be calibrated by measuring the frequency characteristics of the internal circuits in advance.
A method for measuring the frequency characteristic of a waveform generator includes causing a square wave, for example, to be generated from the waveform generator under measurement and acquiring the waveform by using a digitizer serving as a reference, i.e. a digitizer having a flat frequency characteristic. The frequency characteristic of the waveform generator under measurement is calculated based on the waveform data acquired by the digitizer serving as a reference and the waveform data indicating the waveform of the signal generated by the waveform generator.
Furthermore, a method for measuring a frequency characteristic of a digitizer includes causing a square wave, for example, to be generated from a waveform generator serving as a reference, i.e. a waveform generator having a flat frequency characteristic, and acquiring the waveform by using the digitizer under measurement. The frequency characteristic of the digitizer under measurement is calculated based on the waveform data acquired by the digitizer under measurement and the waveform data indicating the waveform of the signal generated by the waveform generator.
However, the frequency component of a square wave has a power that decreases as the frequency increases. Accordingly, when using the methods described above, there is a large error in the frequency characteristic in the high frequency band.